Isotopic dependence of the hydrogen-transfer-triggered methyl-group rotation in deuterated 5-methyltropolone

Ilyushin, V. V.; Johnson, Alyssa M.; Hohl, Jenna A.; Cloessner, Emily A.; Lovas, F. J.; Lavrich, Richard J.

doi:10.1016/j.jms.2017.09.004

Cited by 2 publications

(3 citation statements)

References 11 publications

(52 reference statements)

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“…The higher methyl torsional barrier of 5-methyltropolone is the main reason for the smaller internal rotation splittings. et al studied the deuterated OD isotopologue of 5-methyltropolone, aiming at understanding whether the methyl internal rotation is dependent on subjecting mass changes in the tunneling dimension [217]. Upon OD deuteration, no counterintuitive behavior of the methyl torsion was observed.…”

Section: Internal Rotation Coupled With Ring Inversion Tunnelingmentioning

confidence: 99%

The LAM of the Rings: Large Amplitude Motions in Aromatic Molecules Studied by Microwave Spectroscopy

2022

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Large amplitude motions (LAMs) form a fundamental phenomenon that demands the development of specific theoretical and Hamiltonian models. In recent years, along with the strong progress in instrumental techniques on high-resolution microwave spectroscopy and computational capacity in quantum chemistry, studies on LAMs have become very diverse. Larger and more complex molecular systems have been taken under investigation, ranging from series of heteroaromatic molecules from five- and six-membered rings to polycyclic-aromatic-hydrocarbon derivatives. Such systems are ideally suited to create families of molecules in which the positions and the number of LAMs can be varied, while the heteroatoms often provide a sufficient dipole moment to the systems to warrant the observation of their rotational spectra. This review will summarize three types of LAMs: internal rotation, inversion tunneling, and ring puckering, which are frequently observed in aromatic five-membered rings such as furan, thiophene, pyrrole, thiazole, and oxazole derivatives, in aromatic six-membered rings such as benzene, pyridine, and pyrimidine derivatives, and larger combined rings such as naphthalene, indole, and indan derivatives. For each molecular class, we will present the representatives and summarize the recent insights on the molecular structure and internal dynamics and how they help to advance the field of quantum mechanics.

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Section: Internal Rotation Coupled With Ring Inversion Tunnelingmentioning

confidence: 99%

The LAM of the Rings: Large Amplitude Motions in Aromatic Molecules Studied by Microwave Spectroscopy

2022

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“…The combination of microwave spectroscopy and quantum chemical calculations is an excellent tool to determine the structure and LAM parameters of a molecule, as demonstrated in many cases previously published in the literature. − The two main types of LAMs are inversion tunneling and internal rotation. Some recent investigations on inversion tunneling are, e.g., the proton tunneling in diethyl amine, the ring tunneling in phenyl formate and acetanilide, or the intramolecular hydrogen transfer in 5-methyltropolone . There is a vast amount of examples for internal rotation, such as the methyl internal rotation in 2,4-difluorotoluene, methyl mercaptan, and 5-methyl furfuran …”

Section: Introductionmentioning

confidence: 99%

“…Some recent investigations on inversion tunneling are, e.g., the proton tunneling in diethyl amine, 5 the ring tunneling in phenyl formate 6 and acetanilide, 7 or the intramolecular hydrogen transfer in 5-methyltropolone. 8 There is a vast amount of examples for internal rotation, such as the methyl internal rotation in 2,4-difluorotoluene, 9 methyl mercaptan, 10 and 5-methyl furfuran. 11 Coupled LAMs are reported much more rarely.…”

Section: ■ Introductionmentioning

confidence: 99%

Conformational Effect on the Large Amplitude Motions of 3,4-Dimethylanisole Explored by Microwave Spectroscopy

et al. 2019

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The microwave spectrum of 3,4-dimethylanisole, a molecule containing three methyl groups allowing for internal rotation, was recorded using a pulsed molecular jet Fourier transform microwave spectrometer operating in the frequency range from 2.0 to 26.5 GHz. Quantum chemical calculations yielded two conformers with a trans and a cis configuration of the methoxy group, both of which were assigned in the experimental spectrum. Torsional splittings due to the internal rotations of two methyl groups attached to the aromatic ring were resolved and analysed. The rotation-torsional transitions could be reproduced to measurement accuracy, yielding well-determined rotational and internal rotation parameters. The torsional barriers of the methyl groups at the meta and para position were deduced to be 430.00(37) and 467.90(17) cm −1 , respectively, for the cis-conformer. The respective values for the trans-conformer are 499.64(26) and 533.54( 22) cm −1 . A labelling scheme for the G18 group written as the semidirect product ( 3  3 )⨴ was introduced.

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Isotopic dependence of the hydrogen-transfer-triggered methyl-group rotation in deuterated 5-methyltropolone

Cited by 2 publications

References 11 publications

The LAM of the Rings: Large Amplitude Motions in Aromatic Molecules Studied by Microwave Spectroscopy

The LAM of the Rings: Large Amplitude Motions in Aromatic Molecules Studied by Microwave Spectroscopy

Conformational Effect on the Large Amplitude Motions of 3,4-Dimethylanisole Explored by Microwave Spectroscopy

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